Ornamental · Convolvulaceae
Moonflower
Ipomoea alba
Give it full sun and warm soil, and your moonflower will thank you with fragrant white trumpets each evening.
Full sun
Every 3–7 days
50–90°F · 10–32°C
60–120 days
Overview
Moonflower is a fast, twining vine grown for one lovely thing it does every night. As the light fades, its plump buds spiral open into pure-white, fragrant trumpets as wide as a saucer, welcoming the sphinx and hawk moths that pollinate them, then folding shut again by morning. It sits in the morning glory family and lives much like its day-blooming cousins, only on the opposite clock.
Give it heat and something firm to hold, and it climbs eagerly, easily topping head height in a single summer. In frost-free ground it is a tender perennial, though most gardeners simply grow it as an annual and sow fresh seed each spring. Those scented evening flowers make it a treasured pick for porches, arbors, and any corner you love to sit in after dark.
The good news is that it asks for very little once it settles in, and small missteps are easy to put right. The only two things it truly minds are a cold, short season and soil that is too rich, either of which leaves you with plenty of leaves and few flowers. Get the warmth and the lean soil right, and mostly you are just handing it something to climb.
Care
The short version: full sun, warm and average (not rich) well-drained soil, and steady moisture, with a strong trellis or fence for the vine to climb.
Light
Settle moonflower where it gets full sun, ideally 6 or more hours a day. It will put up with a touch of afternoon shade, but anything short of full sun slows the vine and leaves you with fewer of those flowers.
Water
Keep the soil evenly moist without ever letting it turn soggy, watering about every 3 to 7 days as the heat and rain call for it. It is happiest with steady, medium moisture, and well-drained ground keeps the roots content.
Soil
Plain, well-drained soil is just what it wants, whether that is loam, clay, or sand. Any pH from 6.0 to 7.8 suits it well. Leave out the rich, heavily amended beds, since lush soil grows leaves and quietly holds the flowers back.
Temperature
This one is a true warmth lover, at ease anywhere from 50°F to 90°F (10°C to 32°C). It grows fastest in the heat of high summer and cannot take frost, which ends the plant for the season.
Humidity
Everyday outdoor humidity is more than enough, so you have no target to chase. The vine takes ordinary garden air in stride and needs nothing extra on this front.
Feeding
A light, balanced fertilizer about once a month through the growing season is all this vine asks for. Go gently with nitrogen above all, since a heavy hand grows leaves and pushes back the blooms you are hoping for.
Pruning
Pinch out the young tips early on to encourage the vine to branch and fill out. Past that, simply snip away any dead or stray growth and keep easing the stems onto their support as they climb.
Repotting
In a pot, plan to move it up once a year. Look for roots circling the container, poking out the drainage holes, or growth that stalls, all friendly hints that the plant is ready for more room.
Size & spacing
This is a generous, big vine, climbing 10 to 30 feet (3 to 9 m) in a good season and spreading 3 to 6 feet (91 to 183 cm) wide. Offer it a tall, sturdy trellis, fence, or arbor and plenty of space to roam.
When to plant
Moonflower loves a long run of warmth and gives up at the very first frost, so timing is your friend here. Nick and soak the hard seeds, start them indoors 6 to 8 weeks before your last frost, and move the young plants outside once the cold has truly passed. After that it rewards you with flowers from mid-summer into fall.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Sow: 6-8 weeks before last spring frost, after nicking and soaking the hard seed coat
- Plant: 1-2 weeks after last spring frost once soil is warm
- Harvest: Mid-summer into fall; flowers open at dusk and close by morning
Hardiness
USDA hardiness zones: 10–12
Temperature: down to -1°C
Troubleshooting
Moonflower gives you very little to fuss over, and what does come up usually traces back to the weather or the soil. The most common worry is leaves with no flowers, and now and then a mild pest. Find what matches your plant below and step in early, and you will be fine.
Lots of green growth, but the buds just are not showing
If your vine looks healthy and leafy yet keeps you waiting on flowers, take heart, because the cause is usually simple and easy to correct. Rich soil and too much nitrogen coax out leaves instead of buds, and a cool or shady spot holds the whole plant back. Move it into full sun, lighten up on feeding, and start your seed early so the vine has all the warm weeks it needs to bloom.
Fix:
- Site in full sun with a sturdy support
- Avoid rich soil and high-nitrogen fertilizer
- Start seed indoors early in short-season areas to extend the warm growing window
Curled shoots, freckled leaves, or a wisp of webbing
Do not worry, these little visitors are almost always aphids and spider mites, with a stray caterpillar or leaf miner now and then. Turn a few leaves over and look at the soft new tips, where aphids gather and mites spin a thin web across pale, speckled foliage. A firm spray of water washes most of them away, insecticidal soap takes care of the soft-bodied kind, and any caterpillars come off by hand. On a happy, growing vine, none of this tends to become a real problem.
Fix:
- Dislodge aphids and mites with a strong spray of water
- Treat soft-bodied pests with insecticidal soap
- Handpick caterpillars and remove mined leaves
Toxicity
There is no need to fear this plant, only to handle its seeds with care. Like all morning glories, moonflower carries LSA alkaloids in its seeds, which can make pets, livestock, and people ill and cause a hallucinogenic reaction if swallowed. The leaves are a much gentler concern, but do keep the seeds and pods well away from animals and children.
Toxic to
Cats · Dogs · Horses · Rabbits · Livestock · Birds · People
Cats Mild
The part to watch with cats is the seeds, which hold the LSA alkaloids. A cat that nibbles a few may drool and be sick, and a bigger mouthful can lead to trembling, an unsteady walk, and a dazed look. The leaves are far gentler and rarely a concern.
Dogs Mild
A dog that eats the seeds most often just gets a queasy stomach and vomiting. With a larger amount, the same alkaloids can leave them restless, shaky, and a little spaced-out. On its own, the foliage seldom causes worse than mild tummy upset.
Horses Caution
A horse is not likely to go looking for this vine, but its seeds carry the alkaloids that bother other animals. Keep the seed pods out of reach, and keep an eye out for colic or a dull, off mood if any get eaten.
Rabbits Caution
It is best not to hand moonflower to a rabbit as a treat. The seeds especially can unsettle a delicate gut, so keep the plant and its pods clear of the hutch and run.
Livestock Caution
Cattle, goats, and sheep usually pass by the bitter vine on their own, yet the seeds remain the worry. To be safe, fence grazing animals away from any plants that are setting pods.
Birds Caution
Here too, the seeds are the thing to guard against. Keep pet birds away from any that drop, since eating them can bring on vomiting and a jittery, disoriented spell.
People Caution
No part of this vine is meant for eating, and the seeds are the real danger. Swallowing them brings nausea, vomiting, and hallucinogenic effects from the LSA alkaloids, so tuck the seeds and pods safely out of children's reach.
Keep seeds out of reach of pets and children; ingestion of large amounts of seeds can cause neurologic signs.
Helpline numbers
United States
ASPCA Animal Poison Control: (888) 426-4435 (fee applies)
Poison Control: (800) 222-1222
Canada
Poison Centres: 1-844-764-7669
Varieties
In truth there is just one moonflower, the species itself, though it is often planted beside a day-blooming relative for company. Here are the two worth getting to know.
Ipomoea alba (species moonflower / moonvine)
This is the genuine moonflower, a climbing vine that opens sweetly scented, snow-white trumpets up to 4 to 6 inches wide each evening for the sphinx and hawk moths to visit.
Day-blooming morning glory (Ipomoea purpurea / Ipomoea tricolor)
A friendly relative many gardeners tuck in beside moonflower so there is always something open, since its bright flowers show through the daytime rather than after dark.
Companions
Moonflower pairs naturally with its day-blooming morning glory cousins, which fill the trellis with color while the moonflower sleeps and then hand the night shift back over at dusk.
Plant near
Day-blooming morning glory (Ipomoea purpurea/tricolor): Planted together they provide round-the-clock flowers, day and night.
How to propagate
Moonflower comes from seed, and the one gentle trick is coaxing that tough seed coat to let water through.
SeedEasy
Start indoors 6-8 weeks before last frost or sow outdoors after frost when soil is warm · 1-3 weeks to germinate; rapid growth once weather warms
Growing moonflower from seed is genuinely easy, and the one small step is softening that tough seed coat so water can get in. Nick it with a knife or rub it on sandpaper, then let the seed soak overnight before you plant. Start it indoors 6 to 8 weeks before your last frost, or sow it right outside once the soil feels warm, and you should see sprouts in 1 to 3 weeks before it races away in the heat.
Myths
The climbing moonflower is the very same deadly plant as the jimsonweed or thorn apple that goes by the same name.
These are two different plants that just happen to share the name moonflower. The vine you are growing is Ipomoea alba, a twining morning glory whose seeds hold mildly toxic LSA alkaloids. The truly dangerous one is Datura, an upright nightshade whose tropane alkaloids, atropine, scopolamine, and hyoscyamine, can be fatal. Datura is far more poisonous than the vine, so the shared name really tells you nothing about the risk.